JPH10319176A - Neutron absorber alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and cheaply obtain neutron absorber material superior in neutron absorbing ability, relative strength, corrosion resistivity and processability by adding a specific amount of Hf and Gd in titanium as a parent material. SOLUTION: The neutron absorber alloy of this invention is obtained by adding hafnium and gadolinium of 2 to 40 wt.% so as to be the sum of them in the range of 4 to 50 wt.% in titanium or its alloy as a parent material. Since titanium is superior in relative strength, corrosion resistivity and fabrication capability, does not produce harmful intermetallic compound with hafnium or gadolinium and can contained a plenty of hafnium and gadolinium, a neutron absorber material having more superior neutron absorbing capability than before and superior also in relative strength, corrosion resistivity and processability can be produced easily and cheaply without using any special production method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a neutron absorbing alloy suitable for use in a fuel storage facility such as a nuclear fuel processing plant, a reprocessing plant, a power plant, a fuel transport container, and the like.

[0002]

2. Description of the Related Art Facilities of a facility that handles spent fuel include:
In order to absorb neutrons of spent fuel, boron-containing stainless steel obtained by adding about 1% by weight of boron to stainless steel and boral, which is a composite material of aluminum and B ₄ C, are used.

[0003] In the above-mentioned boron-containing stainless steel, the neutron absorption capacity increases as the boron content increases. However, when the boron content exceeds 1% by weight, the ductility and toughness of the stainless steel are significantly reduced. Specifically, there is a problem that cracks are easily generated in hot rolling at the time of production, and the yield is low because the processing is extremely difficult. As a result, the price increases.

[0004] Further, the stainless steel having a high boron content is susceptible to impacts due to its low ductility and toughness as described above, and is unsuitable as a structural material. There is a problem that it becomes difficult to use such a device.

On the other hand, the above-mentioned boral is excellent in neutron absorption ability, but cannot be processed as a member because it is used as a powder sintered body, and is unsuitable as a structural material due to poor strength and ductility. Further, it has poor corrosion resistance.

[0006]

The substances having excellent neutron absorption properties are Rh, In, Hf, Ir, Sm,
Eu, Gd, Dy, Er, Cd, Hg and B,
Among them, Cd and Hg are highly toxic to the human body, Rh,
Ir is not suitable for use as a neutron absorber because it is a noble metal and is expensive. In addition, some other elements do not produce in large quantities or cannot be put to practical use because of their high price. Materials suitable for the neutron absorber are Hf, S
m, Gd, Dy, Er and B only. Of these, G
d absorbs the neutrons of the thermal energy group very well,
Fast energy neutron absorption is extremely small. Also H
f is the opposite. Therefore, by using these two types in combination, it is possible to produce an alloy having an extremely excellent neutron absorption capacity.

However, when these Gd and Hf are contained in stainless steel, they combine with Ni in the stainless steel to form a low-melting intermetallic workpiece, and the workability and corrosion resistance of the stainless steel are significantly deteriorated.

[0008] The present invention addresses the above-described situation, and includes the required amounts of Hf and Gd in titanium, respectively,
An object of the present invention is to provide a neutron absorbing material having excellent neutron absorbing ability, easy to machine, suitable for a structural material, and excellent in corrosion resistance, easily and inexpensively.

[0009]

That is, the feature of the neutron absorbing alloy of the present invention that meets the above-mentioned object is that titanium is used as a base material, and that 2 to 40% by weight of hafnium (Hf) and 2 to 4% by weight are used.
0% by weight of gadolinium (Gd) is added in such a range that the sum of these hafnium and gadolinium is 4 to 50% by weight of the whole alloy.

[0010]

In the neutron absorbing alloy of the present invention, titanium as a base material is excellent in specific strength, corrosion resistance and workability, and does not form harmful intermetallic compounds between Hf and Gd. Because it can contain a large amount of Gd, it is easy and inexpensive to provide a neutron absorbing material with superior neutron absorption capacity than before and excellent in specific strength, corrosion resistance and workability by ordinary hot working and cold working. It is possible to manufacture.

[0011]

Embodiments of the present invention will be described below.

[0012] Titanium alloys in which the content of hafnium (Hf) and gadolinium (Gd) are variously changed with respect to pure titanium are smelted, respectively, and a sheet material having a thickness of 5 mm is produced for each alloy by hot rolling and heat treatment. Then, the neutron absorption capacity, workability, corrosion resistance and specific strength of these sheet materials were examined. The results are shown in Table 1 below. In the table, based on the conventional stainless steel containing 1% boron,
In comparison with this, particularly excellent was evaluated as ◎, excellent was evaluated as ○, equivalent was evaluated as Δ, and poor was evaluated as ×. (Below)

[0013]

[Table 1]

The neutron absorption capacity in the table is the absorption capacity in the thermal to high-speed neutron range, the workability is the degree of cracking during hot working, the corrosion resistance is the amount of corrosion in high-temperature boric acid water, and the specific strength is the value at room temperature. It is the result which compared each strength with the conventional stainless steel containing 1% boron.

According to the embodiments of the present invention, a titanium alloy for a neutron absorbing material having excellent neutron absorbing ability, workability, corrosion resistance and specific strength as compared with the conventional 1% boron-containing stainless steel is obtained. It is understood that it is possible.

Incidentally, Hf is 2 to 40% by weight and Gd is 2 to 40% by weight.
The reason why the content of Hf and Gd is 2 wt% is 40 wt%.
If the amount is less than 40% by weight, the neutron absorption capacity becomes insufficient as shown in the table, and if the amount exceeds 40% by weight, workability and corrosion resistance deteriorate. The same applies to the sum of Hf and Gd. If the sum is less than 4% by weight, the neutron absorption capacity will be insufficient, and if it exceeds 50% by weight, workability and corrosion resistance will deteriorate.

Although the embodiment of the present invention has been described above, the neutron absorbing alloy of the present invention can be easily processed into a sheet material by general hot working or cold working, and
In use, it is also possible to bend this plate material and use it as it is as a structural material, or to form a thin plate and attach it to, for example, the surface of stainless steel and use it as a composite material. The purity of titanium as a base material is not particularly limited, but it is preferable that the purity is at least equivalent to that of pure titanium for industrial use. Further, it is also possible to use a titanium alloy depending on the application.

[0018]

As described above, the neutron absorbing alloy of the present invention uses titanium or its alloy as a base material,
0% by weight of hafnium and gadolinium are added to each other in a range of a total of 4 to 50% by weight, and the titanium has excellent specific strength, corrosion resistance and workability, and has a good balance between hafnium and gadolinium. A neutron absorbing material that does not generate harmful intermetallic compounds and can contain a large amount of these hafnium and gadolinium, so that it has a better neutron absorbing ability than before and has excellent specific strength, corrosion resistance and workability Has a remarkable effect that it can be simply and inexpensively manufactured without using a special manufacturing method.

Claims (1)

[Claims] 1. Using titanium as a base material, 2 to 40% by weight of hafnium and 2 to 40% by weight of gadolinium, and the total of hafnium and gadolinium is 4 to 5% of the entire alloy.
A neutron-absorbing alloy, characterized by being added in an amount of 0% by weight.